The abundance of crop pests in developing countries may be greatly underestimated, posing a significant threat to some of the world's most important food producing nations, according to research led by the University of Exeter.

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Data on the known distributions of almost 2,000 crop-destroying organisms in 195 countries were analysed in the first global assessment of the factors determining the distribution of crop pests.

Dr Dan Bebber and Professor Sarah Gurr, of the University of Exeter, found that if all countries had levels of scientific and technical capacity similar to the developed world, the number of pests reported would rise greatly and the true extent of the threat would be better understood.

Many developing countries are expected to harbour hundreds of unreported crop pests and diseases, based on current levels of agricultural productivity.

Around one sixth of the world's agricultural production is lost to destructive organisms annually, with further losses post-harvest

Crop pests are often introduced by human activities such as trade and travel, with the wealth of a country linked to the number of invasive species recorded there because – whilst growing rich through trade – they have also accidentally imported pests in agricultural produce.

The Exeter study also considered the link between the wealth of a country (by per capita GDP) and its ability to detect, identify and report the number of crop pests present. Developing countries are less likely to have the capacity to observe invasive species than affluent, technologically-advanced nations.

Monitoring misses hundreds of additional pests and pathogens

Looking at GDP and countries' scientific output as indicators of their pest detection capacity, the study estimated that the pest load of the developing world appears to have been greatly underestimated, and that this may be severely hampering crop protection in some of the world's most important food producing nations.

Dr Dan Bebber commented on the study's wider implications, "Crop pests pose a significant and growing threat to food security, but their geographical distributions are poorly understood," He said.

Dr Bebber continued, "Country wealth is likely to be a strong indicator of observational capacity, not just trade flow, as has been interpreted in previous studies of invasive species. If every country had US-levels of per capita GDP, then on average countries would be reporting more than 200 additional pests and diseases. This suggests that enhanced investment in pest observations will reveal the hidden threat of crop pests and pathogens, as well as bring into focus the opportunity to lose less of the crop by appropriate pest control. The first step to solving crop losses is to identify the pests responsible."

Effects of climate change

The largest numbers of crop pests were reported by the USA, followed by India, China, France and Japan. Island nations reported more pests than coastal and landlocked nations, and the number of pests increased slightly with rainfall.

The study partly follows on from earlier research which looked into the changing distribution of pests and pathogens likely to occur as climate change worsens.

Professor Sarah Gurr added, "When coupled to this [climate change] study we can see that many nations are underestimating pest and pathogen loads. Taken collectively, these papers draw attention not only to the threat of crop disease, and thus global food security, but also to our need for more trained pathologists to inform policy."